The present invention relates to a jig for fixing a bearing on a rotational shaft, and particularly relates to a jig for fixing a bearing with a tapered bore on an end of shaft.
Conventional methods for fixing a bearing with a tapered bore on a rotational shaft are described on pages 92 and 93 of "Korogari-jikuuke no ouyou sekkei" which was published by "Taiga shuppan" on June 1, 1983 and whose author is "Sigeru Ono". In a first method described therein, as shown in FIG. 7A, a collar 4 for setting the bearing on the predetermined position is mounted on an shaft end la and subsequently a tapered adapter sleeve 3 is mounted on the shaft end 1a. As shown in FIG. 7C the tapered adapter sleeve 3 has a screw portion 3a on a thin side thereof and has a plurality of slits 3b extending axially from an end of the thin side to a thick side thereof. The thick side is arranged near the collar 4 in comparison with the thin side.
The bearing 2 with tapered bore, an adapter washer 6 and an adapter nut 5 are mounted on the tapered sleeve 3. The adapter nut 5 engages with the screw portion 3a. When the adapter nut 5 is rotated so that the thick side of the adapter sleeve 3 is moved towards the adapter nut 5 and the tapered outer surface of the adapter sleeve 3 is pressed against the surface of the tapered bore of the bearing 2, the widths of the slits 3b and the diameter of the inner surface of the tapered adapter sleeve 3 are decreased, so that the bearing 2 is fixed on the shaft end 1a by large pressing force generated between the inner surface of the tapered adapter sleeve 3 and the surface of the shaft end la. In order to rotate the adapter nut 5 with large torque for large pressing forces between the bearing 2 and the adapter sleeve 3 and between the bearing 2 and the shaft 1, an engaging tool (not shown) is fitted onto a boss 5a of the adapter nut 5 shown in FIG. 7B and is struck with a hammer. The degree of rotation of the adapter nut 5 is controlled in accordance with the bearing clearance which is the amount of clearances t1 between an outer ring 2a and a rolling element 2c and t2 between an inner ring 2b and the rolling element 2c, as shown in FIG. 7A. The bearing clearance is the average of the horizontal bearing clearance and the vertical bearing clearance. The horizontal bearing clearance is the amount of clearances a and b measured at two positions of the orbital path of the rolling elements 2c on the level of the axis of the shaft 1, as shown in FIG. 7D. The vertical bearing clearance c is measured at the lowest position of the orbital path of the rolling elements 2c. These clearances are measured with a clearance gauge. When the bearing clearance reaches the suitable residual clearance (for example, bearing clearance/shaft diameter is 0.045 mm/100 mm), the rotation of the adapter nut 5 is stopped. Subsequently, the peripheral portion of the adapter washer 6 is bent and engages with the adapter nut 5, so that the adapter nut 5 is fixed.
In a second method, the shaft 1 has a screw portion 7 at the outer side of the shaft end 1a, as shown in FIG. 8. The collar 4 contacting with a step portion of the shaft 1 for setting the bearing 2 on the predetermined position is mounted on the shaft end 1a and subsequently the tapered adapter sleeve 3' is mounted on the shaft end 1a. The tapered adapter sleeve 3 has a screw portion 3a' on a thick side thereof and has a plurality of slits 3b' extending axially from an end of a thin side to the thick side thereof. The thin side is arranged near the collar 4 in comparison with the thick side. The one end of the inner ring 2b contacts with the end of the collar 4. A removable sleeve 8 is mounted on the screw portion 7. The removable sleeve 8 has a plurality of bolts 9 arranged at the peripheral portion. The tapered sleeve 3' is pressed towards the collar 4 by the bolts 9 rotated suitably so that the bearing 2 is fixed on the shaft 1 through the tapered sleeve 3' pressed between the shaft 1 and the bearing 2. The degrees of rotation of the bolts 9 are controlled in accordance with the bearing clearance, as described in the first method. When the bearing clearance reaches the suitable residual clearance, the rotations of the bolts 9 are stopped.
In the first method described above, the positional relation between the bearing 2 and the shaft 1 is correct but the bearing 2 can not be fixed at the correct position of the bearing housing. And further, in order to rotate the adapter nut 5 for drawing the sleeve 3, means for preventing the shaft 1 from rotating on its own axis is necessary.
In the second method described above, as the first method, the positional relation between the bearing 2 and the shaft 1 is correct but the bearing 2 can not be fixed at the correct position of the bearing housing. And the means for preventing the shaft 1 from rotating on its own axis is not necessary but the additional shaft portion with screw which is used only for pressing the tapered sleeve 3' and which is not used after fixing the bearing 2 is necessary.